Support arm and method with variable counterbalance

ABSTRACT

A support arm includes an arm having a proximal arm pivot joint that provides a range of elevational rotation of the arm. The arm further includes a distal component mount. The support arm further includes a biasing device adapted to provide an increasing force with increasing displacement. A flexible element is coupled between the biasing device and the arm with a linkage therebetween. At least a portion of the flexible element forms a segment between the arm and the linkage. The segment is at an angle relative to the arm, and the angle varies during rotation of the arm. An arm end location of the segment is fixed in relation to the arm during rotation of the arm. A linkage end location of the segment changes in relation to the pivot joint during rotation of the arm.

FIELD OF THE INVENTION

This application relates to devices and methods for moveably supporting equipment. Specifically, but not by way of limitation, this application relates to devices and methods for supporting display screens such as flat panel display screens for use with personal computers.

BACKGROUND

In many fields, it is useful to support equipment in such a way to make the position of the equipment adjustable. In particular, flat panel display screens (e.g., LCD screens, plasma screens and the like) are gaining popularity with consumers. It is desirable for users of flat panel display screens to position their screens, in orientations that are ergonomically correct, for instance at eye level.

Although examples of the present invention can be used with several different adjustment joints, an elevation joint is used as an example. An elevation adjustment is useful to provide flexibility for users of different heights. One common elevation adjustment includes an arm configuration with a joint between two arm portions. A user can move a distal arm portion along an arc by rotating the distal arm in relation to a base arm portion about an elevation joint.

It is inconvenient for the user if the equipment, such as the flat panel display, does not stay in the intended position. Unwanted motion can be caused by the elevation joint being too loose, with the equipment moving under its own weight. Additionally, sometimes the mechanism of the arm overcompensates or undercompensates for the weight of the display screen and/or the arm, and the arm undesirably moves out of the desired position on its own. Unwanted motion can also be caused by inadvertent bumping of the arm or supported equipment. Further, if the elevation joint moves an excessive amount, the supported equipment, such as the flat panel display, may become damaged by hitting a surface such as a desktop.

What is needed is a support arm that provides adjustability and retains the display screen in a desired orientation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one example of a support arm supporting a display screen.

FIG. 2 shows one example of a support arm with a chassis.

FIG. 3 shows one example of a support arm in a first position.

FIG. 4 shows another example of the support arm in a second position.

FIG. 5 shows a free body diagram and static equations of one example of a support arm.

FIG. 6 shows a graph displaying one example of the moments of the support arm shown in FIG. 5 relative to the moments created by the support arm weight over a range of support arm angles.

FIG. 7 shows a graph displaying one example of the moments of a prior art gas spring support arm relative to the moments created by the support arm weight over a range of support arm angles.

FIG. 8 shows one example of a support arm in a first position.

FIG. 9 shows another example of the support arm in an intermediate position.

FIG. 10 shows yet another example of the support arm in a second position.

FIG. 11 shows a graph displaying the arm angle against the angle of the cable Φ.

FIG. 12 shows a block diagram for one example of a method for making a support arm.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical changes, etc. may be made without departing from the scope of the present invention.

FIG. 1 shows a support arm 100 and a display screen 102 coupled to the support arm 100. In one example, the display screen 102 is a flat panel display, for instance, a plasma television, LCD display, or the like. In another example, the display screen 102 is a CRT display, LCD projection display or the like. The support arm 100 is optionally mounted to a surface, such as a wall, floor, ceiling and the like. In yet another example, the support arm 100 is mounted to a chassis, for instance, a wheeled chassis, such as the chassis 200 shown in FIG. 2, described below. The support arm 100 is positionable so the display screen 102 coupled at the distal end 104 of the support arm 100 is similarly positionable. In one example, the display screen 102 is positionable vertically through movement of the support arm 100. In another example, the display screen 102 is positionable horizontally through rotation of the support arm 100 around a pole, bar, wall and the like.

As shown in FIG. 1, the distal end 104 of the support arm 100 includes a distal component mount 106 sized and shaped to couple with the display screen 102. The distal component mount 106 includes, in another example, a lug 108 sized and shaped to movably couple with the display screen 102. The lug 108 couples with a corresponding display lug 110 of the display screen 102 to facilitate rotational movement of the display screen 102 around the distal end 104. The display lug 110 rotates relative to the lug 108 of the mount 106, optionally. The display screen 102 is thereby further positionable so the screen 102 points upward and/or downward relative to a horizontal axis 112. In still another example, the display screen 102 includes features to mount directly to the support arm 100 so the display screen 102 includes the distal component mount 106.

FIG. 2 shows the support arm 100 coupled with the chassis 200. In one example, the chassis 200 includes a housing 202. The housing 202, as shown in the example in FIG. 2, is formed with bars and/or plates assembled to provide a first shelf 204 for an input device, such as, a keyboard, mouse, light pen, and the like. The housing 202 provides a second shelf 208 for a processor. Optionally, the housing includes additional shelves and storage devices, for instance, document shelf 206. In another example, the housing 202 includes a mount 210 sized and shaped to couple with the support arm 100. The support arm 100 extends from at least a portion of the housing 202 and is proximate to the first shelf 204, optionally. The display screen 102 is thereby proximate to a keyboard or other input device and allows for operation of the input device and viewing of the display screen 102 at the same time. In yet another example, the support arm 100 is remote from the first shelf 204 to allow remote viewing of the display screen (e.g., while pointed in a different direction for the benefit of a second viewer). The display screen 102, input devices and a processor are in communication with each other, in still another example.

In another option, the housing 202 rides on casters 212 sized and shaped to facilitate movement of the chassis 200. The casters 212 permit movement of the display screen 102 into a variety of locations and the support arm 100 facilitates stable positioning of the display screen 102 into a variety of orientations for ease of viewing during use.

FIG. 3 shows the support arm 100 in a first position. The support arm 100, in one example, includes a four bar linkage 300 including arms, such as members 302A, B. The members 302A, B are moveably coupled between the distal component mount 106 and a proximal mount 304. The member 302A is moveably coupled to the proximal mount 304 at a pivot joint 307. The proximal mount 304 is sized and shaped to facilitate coupling with, for instance, walls, ceilings, floors, poles, chassis (e.g., chassis 200) and the like. The members 302A, B are offset from each other and moveably coupled to the distal component mount 106 and the proximal mount 304. The four bar linkage 300 thereby permits movement of the support arm 100 between at least the positions shown in FIGS. 3 and 4. Optionally, the support arm 100 moves between angles of at least around 90 to −90 degrees. In one example, the members 302A, B are coupled with the distal component mount 106 and the proximal mount 304 with fasteners such as pins, screws, rivets, and the like that permit rotation of the members at the mounts 106, 304. In another example, the members 302A, B are parallel to each other throughout movement of the support arm 100.

A biasing device 306, in one example, is coupled to the member 302B. The biasing device 306 provides a restoring force that increases with increased displacement of the device 306 (e.g., compression and/or extension). The biasing device 306 includes, but is not limited to, compression springs, tension springs, elastomeric materials and the like. The biasing device 306 is constructed with a material, such as steel, an elastomer and the like, that provides restoring force to retain the support arm 100 in a desired orientation. Optionally, the biasing device 306 includes springs and/or elastomeric material in combinations (e.g., in series, parallel, tension and compression springs together, and the like). As shown in FIGS. 3 and 4, the biasing device 306 is optionally coupled at a first end 308 to the member 302B. The biasing device 306 is coupled to the member 302B with, but not limited to, fasteners such as pins, welds, lugs and the like. In one option, the first end 308 of the biasing device 306 is moveably coupled along the member 302B. For example, the biasing device 306 is coupled to the member 302B with bolts, screws, detents and the like that allow adjustment of the first end 308 location along the member 302B. Positioning of the biasing member 306 thereby tunes the member 306 to provide a desired amount of pretensioning to the support arm 100. In another example, a second end 310 of the biasing device 306 is moveably coupled to a first pulley 312 to permit rotation of the pulley 312 relative to the biasing device 306. Optionally, the first pulley 312 forms a linkage that supports a flexible element, described below.

A flexible element 314, such as a filament, cable, belt and the like, extends between the members 302A, B. In one example, the flexible element 314 is coupled to the member 302B distal to the proximal mount 304. In another example, the flexible element 314 is coupled to the member 302A proximate to the distal component mount 106. As shown in FIG. 3, the first pulley 312 is in rolling communication with the flexible element 314. Movement of the support arm 100 including the members 302A, B correspondingly moves the flexible element 314 over the first pulley 312 and pushes or pulls the first pulley 312 coupled to the biasing device 306. Movement of the flexible element 314 during rotation of the support arm 100 thereby increases or decreases the restoring force provided by the biasing device 306 by pulling or pushing on the first pulley 312 coupled thereto. The flexible element 314 is coupled along the members 302A, B so the restoring force applied by the biasing device 306 to the support arm 100 increases as the moment of the support arm 100 increases, for instance while the support arm 100 is in a substantially horizontal position (i.e., between the first and second position in FIGS. 3 and 4, respectively). A component of the restoring force created by the biasing device 306 provides a moment that counterbalances the moment of the display screen 102 (FIG. 1) and the support arm 100 and maintains the display screen 102 and the support arm 100 in a desired orientation, as further described below.

As shown in FIGS. 3 and 4, a second pulley 316 is moveably coupled to the member 302B, in one example. In the example shown, the second pulley 316 is rotatably coupled to the member 302B and carried on a bearing, such as a circular pin. The second pulley 316, as part of the linkage optionally including the first pulley 312, provides a mechanical advantage to movement of the flexible element 314 and the biasing device 306. The second pulley 316 allows the flexible element 314 to experience double the displacement relative to the displacement of the biasing device 306. This minimizes the space taken up by the biasing device 306 along the support arm 100 because the biasing device 306 is able to counterbalance the moment of the support arm 100 with half of the displacement of the flexible element 314. As a result, the linkage, including the first pulley 312 and the second pulley 316, provides a compact design for the support arm 100 that provides sufficient restoring force to supply a moment that counterbalances the moment of the arm 100 and/or the display screen 102 (FIG. 1). The support arm 100 thereby presents a narrow profile that takes up less space and also maintains the desired position of the arm 100 and/or the display screen 102. In another example, the linkage includes, cams, levers and the like, adapted to assist in maintaining the support arm 100 in a desired orientation.

As shown in FIGS. 3 and 4, the angle Φ extends between member 302A and a segment 315 of the flexible element 314. In one example, the flexible element segment 315 extends between an arm end location 318 on the member 302A and a linkage end location 319 where the flexible element 314 movably couples with the second pulley 316. The linkage end location 319 is optionally at a tangent to the circumference of the second pulley 316 where the segment 315 meets the pulley 316. During rotation of the support arm 100, the distance between the arm end location 318 and the pivot joint 307 is static and the distance between the linkage end location 319 and the pivot joint 307 changes. For instance, the linkage end location 319 will change as the tangent changes along the second pulley 316. In another example, the arm end location 318 is static along the member 302A. The angle Φ changes with rotation of the support arm 100 because the arm end location 318 moves relative to the second pulley 316 (See FIGS. 3 and 4) and the linkage end location 319 changes. The segment 315 of the flexible element 306 between the arm end location 318 and the second pulley 316 thereby changes length during rotation of the support arm 100. The component of the restoring force applied to the support arm 100 to create a counter balancing moment changes during rotation of the arm 100 according to the angle Φ.

The arm end location 318 and the placement of the second pulley 316 along the member 302B are chosen so the angle Φ changes in a predetermined manner. The angle Φ changes in the predetermined manner to ensure the biasing device 306 provides a restoring force and corresponding moment that closely counterbalances the moment of the arm 100 and/or the display screen 102 (FIG. 1) during rotation of the arm 100. As a result, the biasing device 306 and the flexible element 314 substantially counterbalance the moment of the support arm 100 and/or the display screen 102 (FIG. 1) throughout the range of motion of the arm 100. In another example, the support arm 100 (e.g., the arm end location 318 and the linkage end location 319 are chosen so the angle Φ changes at different rates during rotation of the arm 100. For instance, the rate of change of the angle Φ increases at least after the arm 100 passes a substantially horizontal position between the first and second positions (FIGS. 3 and 4) and moves into orientations such as that shown in FIG. 3 (i.e., where the arm 100 is angled below horizontal). The angle Φ decreases at an increased rate to attenuate the increased restoring force of the biasing device 306 as the arm 100 is rotated. The biasing device 306 experiences increased displacement during rotation of the arm and the device 306 correspondingly produces greater restoring forces. The angle Φ decreases at a greater rate to attenuate the corresponding moment due to the greater restoring force. As a result, the decreasing moment of the arm 100 and/or the display screen 102 (FIG. 1) coupled thereto in orientations such as shown in FIG. 3 is matched by the attenuated moment created by the displaced biasing device 306 and the angle Φ that decreases at a faster rate.

In another option, the segment 315 of the flexible element 314 is coupled to the member 302A with a stop 320 sized and shaped to engage with the member 302A and substantially prevent movement of the segment 315 at the arm end location 318. In one example, the flexible element 314 is threaded through the member 302A with the stop 320 coupled to the element 314. The stop 320 has a larger profile than the element 314 and engages with the member 302A to couple the flexible element 314 to the member 302A. Optionally, the stop 320 includes, but is not limited to, a piece of plastic, metal and the like formed around the flexible element 314. In another option, the stop 320 includes a swaged portion of the flexible element 314 that presents a larger profile than the flexible element 314. In another example, the stop 320 is positionable along the member 302A while the support arm 100 is not being rotated. The stop 320 is positioned, for instance, within detents, grooves, spaced sockets and the like to selectively position an end of the segment 315 at varying arm end locations 318. The position of the arm end location 318 relative to the second pulley 316 correspondingly changes the length of the segment 315. Additionally, the position of the arm end location 318 relative to the second pulley determines how the angle Φ changes in the predetermined manner to alter the restoring force of the support arm 100 during rotation. Movement of the arm end location 318 toward the proximal mount 304 correspondingly increases the angle Φ throughout the travel of the support arm 100. As a result, the component of the restoring force of the biasing device 306 used to counterbalance the moment of the support arm 100 and/or the display screen 102 increases, as described below. Additionally, movement of the arm end location 318 toward the distal mount 106 increases the moment created by the restoring force because the moment arm 322 is correspondingly increased (also described below). Optionally, the arm end location 318 is chosen to optimize the component of the restoring force and the moment arm 322 that provide the moment to counterbalance the moment of the support arm 100 and/or the display screen 102.

FIG. 5 shows one example of a support arm free body diagram including representations of the members 302A, B, the distal mount 106 and the proximal mount 304. The biasing device includes a compression spring 500 in the example shown. The compression spring 500 provides an F_(sp) and pulls on the flexible element 314 to put the element 314 in tension as shown with F_(cable). As shown in FIG. 5, the segment 315 of the flexible element 314 extends between the linkage end location 319 at the second pulley 316 and the arm end location 318. F_(cable) is applied to the member 302A at the arm end location 318. A component of F_(cable) and the moment arm 1 m (e.g., moment arm 322 in FIGS. 3 and 4) provide the moment M_(sp) around pivot joint 502 between the proximal mount 304 and the member 302A. The moment of the weight M_(W) is provided by the weight W including the weight of the support arm 100 and/or the weight of the display screen 102 (FIG. 1). As shown in the free body diagram and the example equations in FIG. 5, the M_(sp) acts to counterbalance the M_(W) of the support arm 100 and/or the display screen 102.

The arm end location 318, where the flexible element 314 couples with the member 302A, is chosen to optimize the moment arm 1 m and the angle Φ and thereby provide a M_(sp) that closely counterbalances the M_(W) throughout rotation of the support arm 100. The angle Φ determines the component of the F_(cable) used in providing the M_(ps) as shown in FIG. 5. As described above, the arm end location 318 is chosen so the angle Φ changes in a predetermined manner to ensure the component of the F_(cable) and the moment arm 1 m provide sufficient M_(sp) to counterbalance the M_(W) substantially throughout rotation of the support arm 100. In another example, the linkage end location 319 and the arm end location 318 are chosen so the angle Φ changes in a predetermined manner. In yet another example, the support arm 100 is sized and shaped so the angle Φ changes at a faster rate during rotation of the arm 100 through a particular angle (e.g., where the arm moves from the horizontal to negative angles as shown in FIG. 3). As the angle Φ changes at the faster rate increased restoring forces from the biasing device 306 are attenuated to ensure the arm 100 maintains the display screen in a desired orientation, as described below.

In one example, a first arm end location 318 is chosen so M_(sp) counterbalances the support arm 100 and a display screen 102 (FIG. 1) that has a particular weight and depth (e.g., is shallow or deep and thereby decreases or increases the moment arm of the M_(W)). In another example, the first arm end location 318 is adjusted so M_(sp) counterbalances the support arm 100 and a display screen 102 with a different weight and/or depth.

FIG. 6 shows a graph 600 comparing one example of the M_(sp) generated with a support arm, such as support arm 100 (FIG. 1), along with the corresponding M_(W) provided by the support arm 100 and/or the display screen 102 (FIG. 1) during rotation of the arm 100. The curve of the M_(sp) closely approximates the curve of the M_(W) thereby showing the M_(sp) closely counterbalances the M_(W). As a result, the support arm 100 maintains the display screen 102 in a desired orientation. FIG. 7 shows a graph comparing a prior art support arm with the M_(W) of the prior art support arm and/or a display screen. The prior art support arm M_(sp) curve shows that the M_(sp) is consistently greater than the M_(W). The prior art support arm thereby overcompensates for the M_(W) of the support arm and/or the display. The prior art support arm may undesirably move the display screen from a desired orientation because the prior art arm does not ensure the close counterbalancing provided with the support arm 100 (FIG. 6).

In operation, the support arm 100 is rotated around the proximal mount 304. The member 302A rotates around the pivot joint 307 and the member 302B similarly rotates with member 302A around an offset joint 309. Rotation of the support arm 100 from the position shown in FIG. 3 to the position shown in FIG. 4 moves the arm end location of the segment 315 closer to the linkage end location 319. In one example, the flexible element 314 correspondingly moves over the second pulley 316 and allows the biasing device 306 to relax, as shown in FIG. 4. As the biasing device 306 relaxes it progressively applies less restoring force to the support arm 100. As described above, the angle Φ changes during rotation of the support arm 100. The angle Φ changes in a predetermined manner and the component of the restoring force used to provide the counterbalancing moment (e.g., M_(sp)) to the moment of the support arm 100 and/or the display screen 102 (e.g., M_(W)) correspondingly changes. The counterbalancing moment changes during rotation of the support arm 100 to closely counterbalance the support arm 100 and/or the display screen 102 (FIG. 1). As a result, the support arm 100 maintains a desired orientation of the display screen 102, throughout the range of motion of the arm 100.

In another example, movement of the support arm 100 from a position, such as the position shown in FIG. 4, to the position shown in FIG. 3 moves the arm end location 318 away from the linkage end location and thereby displaces the biasing device 306 because the flexible element 314 is displaced. The biasing device 306 applies additional restoring to the flexible element 314. The angle Φ changes in the predetermined manner so the component of the restoring force used in the counterbalancing moment changes and the moment closely counterbalances the moment of the support arm 100 and/or the display screen 102. The support arm 100 thereby maintains the display screen 102 in the desired orientation.

Optionally, the arm end location 318 of the segment 315 is changed to vary the moment arm 322 applied with the restoring force of the biasing device 306 to create the counterbalancing moment. Movement of the arm end location 318 also changes the angle Φ and thereby changes the component of the restoring force used in the counterbalancing moment. The arm end location 318, in one option, is chosen to optimize the moment arm 322 for the counterbalancing moment and also to optimize the component of the restoring force used to generate the moment.

Another example of the support arm 800 is shown in FIGS. 8, 9 and 10. The support arm 800 is similar to the support arm 100 in at least some aspects. The support arm 800 is positionable so the display screen 102 (FIG. 1) coupled at the distal end 804 of the support arm 800 is similarly positionable. In one example, the display screen 102 is positionable vertically through movement of the support arm 800. In another example, the display screen 102 is positionable horizontally through rotation of the support arm 800 around a pole, bar, wall and the like.

As shown in FIGS. 8, 9 and 10, the distal end 804 of the support arm 800 includes a distal component mount 806 sized and shaped to couple with the display screen 102 (FIG. 1). The distal component mount 806 includes, in another example, a hinged lug 808 sized and shaped to movably couple with the display screen 102. The hinged lug 808 couples with the display screen to facilitate rotational movement of the display screen 102 around the distal end 104. In one example, the hinged lug 808 permits rotation around at least axes 809, 811. In another example, the hinged lug 808 permits rotation around one or more axes. In still another example, the display screen 102 includes features to mount directly to the support arm 800 so the display screen 102 includes the distal component mount 806.

FIGS. 8, 9 and 10 show the support arm 800 in first, intermediate and second positions. The support arm 800 is movable within at least the range shown, in one example. In another example, the support arm 800 is movable within a range of at least around 90 to −90 degrees relative to the relatively horizontal position shown in FIG. 9 (i.e., 0 degrees). The support arm 800, in one example, includes a four bar linkage 824 including arms, such as members 826A, B. The members 826A, B are moveably coupled between the distal component mount 806 and a proximal mount 828. The member 826A is moveably coupled to the proximal mount 828 at a pivot joint 807. The proximal mount 828 is sized and shaped to facilitate coupling with, for instance, walls, ceilings, floors, poles, chassis (e.g., chassis 200) and the like. The members 826A, B are offset from each other and moveably coupled to the distal component mount 806 and the proximal mount 828. The four bar linkage 824 thereby permits movement of the support arm 100 between at least the positions shown in FIGS. 8, 9 and 10.

As described with the support arm 100, a biasing device 830, in one example, is coupled to the member 826B of the support arm 800. The biasing device 830 provides a restoring force that increases with increased displacement of the device 830 (e.g., compression and/or extension). The biasing device 830 includes, but is not limited to, compression springs, tension springs, elastomeric materials and the like. Optionally, the biasing device 830 includes springs and/or elastomeric material in combinations (e.g., in series, parallel, tension and compression springs together, and the like). As shown in FIGS. 8, 9 and 10, the biasing device 830 is optionally coupled at a first end 832 to the member 826B. The biasing device 830 is coupled to the member 826B with, but not limited to, fasteners such as brackets, pins, welds, lugs and the like. As shown in FIGS. 8, 9 and 10, the biasing device 830 is coupled to the member 826B with a bracket 834. In one option, the first end 832 of the biasing device 830 is moveably coupled along the member 826B. For example, the biasing device 830 is coupled to the member 826B with bolts, screws, detents and the like that allow adjustment of the first end 832 location along the member 826B. Positioning of the biasing member 830 thereby tunes the member 830 to provide a desired amount of pretensioning to the support arm 800 allowing positioning of a variety of display screens.

In another example, a second end 836 of the biasing device 830 is moveably coupled to a first pulley 838 to permit translational movement of at least the second end 836, as described below. Optionally, the first pulley 838 forms a linkage that supports a flexible element, described below. In another option, the first pulley 838 is positioned within the biasing device 830 (e.g., within the coils of a spring). The first pulley 838 is coupled with the basing device 830 by a bearing 840 extending between the pulley 838 and the second end 836 of the biasing device 830. A guide 842, in yet another option, extends from the second member 826B (e.g., the bracket 834) along the biasing device 830. In one example, the guide 842 is disposed within at least one of the bearing 840 and the biasing device 830. The guide 842 thereby substantially prevents lateral movement of the biasing device 830 during displacement of the device 830. The guide 842 is slidably coupled with the biasing device 830 and/or the bearing 840 and permits longitudinal displacement (e.g., contraction and extension) of the biasing device 830, as described below.

A flexible element 844, such as a filament, cable, belt and the like, extends between the members 826A, B. The flexible element 844 is constructed with, but not limited to, metal (e.g., steel), polymers, rope and the like. In one example, the flexible element 844 is coupled to the member 826B distal to the proximal mount 828. The flexible element 844 is coupled to the bracket 834, in another example. The flexible element 844 is coupled with, but not limited to, a fastener such as a lug 846, weld, pin and the like. In another example, the flexible element 844 is coupled to the member 826A proximate to the distal component mount 806.

As shown in FIGS. 8, 9 and 10, the first pulley 838 is in rolling communication with the flexible element 844. Movement of the support arm 100 including the members 826A, B correspondingly moves the flexible element 844 over the first pulley 838 and pulls or relaxes pulling on the first pulley 838 coupled to the biasing device 830 (e.g., through the bearing 840). Movement of the flexible element 844 during rotation of the support arm 800 thereby increases or decreases the restoring force provided by the biasing device 830 by displacing the biasing device 830 with pulling or relaxing of pull on the first pulley 838 coupled thereto.

As described with somewhat similar components in the support arm 100, the flexible element 844 is coupled along the members 826A, B so the restoring force applied by the biasing device 830 to the support arm 800 increases as the moment of the support arm 800 increases, for instance while the support arm 100 is in a substantially horizontal intermediate position as shown in FIG. 9 (i.e., between the first and second positions in FIGS. 8 and 10, respectively). A component of the restoring force created by the biasing device 830 provides a moment that counterbalances the moment of the display screen 102 (FIG. 1) and the support arm 800 and maintains the display screen 102 and the support arm 800 in a desired orientation, as further described below.

As shown in FIGS. 8, 9 and 10, a second pulley 848 is coupled between the second member 826B and the proximal mount 828, in one example. In the example shown, the second pulley 848 is rotatably coupled to the pivot joint 850 and carried on a bearing, such as a circular pin. The second pulley 848, as part of the linkage optionally including the first pulley 838, provides a mechanical advantage to movement of the flexible element 844 and the biasing device 830. The second pulley 848 allows the flexible element 844 to experience double the displacement relative to the displacement of the biasing device 830. This minimizes the space taken up by the biasing device 830 along the support arm 800 because the biasing device 830 is able to counterbalance the moment of the support arm 800 with half of the displacement of the flexible element 844. As a result, the linkage, including the first pulley 838 and the second pulley 848, provides a compact design for the support arm 800 that provides sufficient restoring force to supply a moment that counterbalances the moment of the arm 800 and/or the display screen 102 (FIG. 1). The support arm 800 thereby presents a narrow profile that takes up less space and also maintains the desired position of the arm 800 and/or the display screen 102. In another example, the linkage includes, cams, levers and the like, adapted to assist in maintaining the support arm 800 in a desired orientation.

The arm end location 852 and the placement of the second pulley 848 along the member 826B are chosen so the angle Φ changes in a predetermined manner. The angle Φ changes in the predetermined manner to ensure the biasing device 830 provides a restoring force component and corresponding moment that closely counterbalances the moment of the arm 800 and/or the display screen 102 (FIG. 1) during rotation of the arm 800. As a result, the biasing device 830 and the flexible element 844 substantially counterbalance the moment of the support arm 800 and/or the display screen 102 (FIG. 1) throughout the range of motion of the arm 800. In another example, the arm end location 852 and the linkage end location 854 (e.g., where the flexible element 844 is tangent to the second pulley 848 and extends toward the arm end location 852) are chosen so the angle Φ changes at different rates during rotation of the arm 100. For instance, the rate of change of the angle Φ increases at least after the arm 800 passes a substantially horizontal position between the first and second positions (FIG. 9) and moves into orientations such as that shown in FIG. 10 (i.e., where the arm 800 is angled below horizontal). The angle Φ decreases at an increased rate to attenuate the increased restoring force of the biasing device 830 as the arm 800 is rotated. The biasing device 830 experiences increased displacement during rotation of the arm and the device 830 correspondingly produces a greater restoring force component for the counter-balancing moment. The angle Φ decreases at a greater rate to attenuate the corresponding moment due to the greater restoring force. As a result, the decreasing moment of the arm 800 and/or the display screen 102 (FIG. 1) coupled thereto in orientations such as shown in Figures and 10 is matched by the attenuated moment created by the displaced biasing device 830 and the angle Φ that decreases at a faster rate. The support arm 100 is sized and shaped to provide a similar relation for angle Φ, in another example.

In another option, the segment 856 of the flexible element 844 is coupled to the member 826A with a stop 858 sized and shaped to engage with the member 826A and substantially prevent movement of the segment 856 at the arm end location 852. As described above for the stop 320, optionally, the stop 858 includes, but is not limited to, a piece of plastic, metal and the like formed around the flexible element 844. In another option, the stop 858 includes a swaged portion of the flexible element 844 that presents a larger profile than the flexible element 844. In one example, the flexible element 844 is threaded through a keeper 860 with the stop 858 coupled to the element 314. The keeper 860, in another example, is moveable along the member 826A, for instance along a rail 862. In still another example, the rail 862 includes a bolt, pin and the like sized and shaped to move along the member 826A and thereby move the arm end location 852 (e.g., the keeper 860).

The position of the arm end location 852 relative to the second pulley 848 correspondingly changes the length of the segment 856. Additionally, the position of the arm end location 852 relative to the second pulley 848 determines how the angle Φ changes in the predetermined manner to alter the restoring force of the support arm 800 during rotation. Movement of the arm end location 852 toward the proximal mount 828 correspondingly increases the angle Φ throughout the travel of the support arm 800. As a result, the component of the restoring force of the biasing device 830 used to counterbalance the moment of the support arm 800 and/or the display screen 102 increases. Additionally, movement of the arm end location 852 toward the distal mount 806 increases the moment created by the restoring force because the moment arm 864 is correspondingly increased. Optionally, the arm end location 852 is chosen to optimize the component of the restoring force and the moment arm 864 that provide the moment to counterbalance the moment of the support arm 800 and/or the display screen 102.

FIG. 11 is a graph 1100 displaying the angle of a support arm, such as support arm 800, compared with the angle of the segment 856 relative to the first member 826A (i.e., angle Φ). Angle Φ increases as the support arm 800 approaches the 0 degree position where the support arm 800 and/or the display screen 102 (FIG. 1) provide the largest moment (See FIG. 9). The angle Φ reaches its peak at the support arm 800 position shown in FIG. 9, the 0 degree position of the arm 800. At this position, the angle Φ allows the biasing device 830 to apply the appropriate amount of restoring force as the component of counterbalancing moment to maintain the arm 800 in the desired position. As the support arm 800 is positioned beyond the position shown in FIG. 9 (i.e., negative angle measures) the angle Φ decreases at a faster rate. As described above, the angle Φ decreases at a faster rate to offset the continued displacement of the biasing device 830 and corresponding increased restoring force component of the counter-balancing moment. The smaller angle Φ in the negative arm angles (e.g., the position shown in FIG. 10) ensures a smaller component of the increased restoring force is applied to the support arm 800. Because the support arm 800 and/or the display screen 102 (FIG. 1) create smaller moments at the negative arm angles, the attenuated component of the restoring force does not overbalance the support arm 800. In one example, the support arm 800 (e.g., arm end location 852, linkage end location 854 and the like) is sized and shaped to ensure the angle Φ attenuates the moment created by the biasing device 830 in a predetermined manner that closely offsets the moment of the support arm 800 and/or the display screen 102.

FIG. 12 is a block diagram illustrating a method 1200 for making a support arm. Examples of a support arm (i.e., support arms 100, 800) is shown in FIGS. 1-4 and 8-10. Reference is made to the support arm 100 below. In another example, the method 1200 applies to the support arm 800. At 1202, a flexible element 314 is coupled between a biasing device 306 and a first member 302A. In one example, another portion of the flexible element 314 is coupled to a second member 302B. The second member 302B is adapted to correspondingly move with the first member 302A. The first member 302A includes a pivot joint 307 around which the first member 302A rotates. The biasing device 306 includes, but is not limited to a compression spring, tension spring, elastomeric material and the like. Optionally, the biasing device 306 includes springs and/or elastomeric material in combinations (e.g., in series, parallel, tension and compression springs, and the like). The biasing device 306 provides an increasing force with increasing displacement. In another option, a first end 308 of the biasing device 306 is coupled to the second member 302B.

At 1204, a linkage is moveably coupled along the flexible element between first member 302A and the biasing device 306. At least a portion of the flexible element 314 forms a segment 315 between the first member 302A and the linkage and the segment 315 is at an angle relative to the first member 302A (e.g., angle Φ). The angle varies during rotation of the first member 302A. An arm end location 318 is fixed in relation to the first member 302A during rotation and a linkage end location 319 of the segment 315 changes in relation to the pivot joint 307 during rotation. In one example, the linkage includes at least one pulley 316 moveably coupled along the flexible element 314. The at least one pulley 316 is coupled to the second member 302B, in another example. In yet another example, the linkage includes cams, levers and the like adapted to assist in positioning the support arm 100 in a desired orientation.

Optionally, the support arm 100 includes an additional pulley 312 coupled between the biasing device 306 and the flexible element 314. The additional pulley 312 is moveably coupled to the flexible element 314 so the pulley 312 is in rolling communication with the flexible element 314.

CONCLUSION

Using embodiments described above, a number of advantages are realized. One advantage includes a support arm that provides a moment that closely counterbalances the moment of the support arm and/or a display screen throughout the range of motion of the support arm. Because the support arm closely counterbalances the moment of the arm and/or the display screen, the arm remains in a desired orientation anywhere along the range of motion of the arm. Additionally, because the angle Φ decreases at a higher rate after at least passing the point of maximum moment of the support arm and/or the display screen (e.g., 0 degrees) the support arm attenuates the increased restoring force of the biasing device and closely matches the decreased moment of the support arm and display screen. Moreover, because the biasing device and the linkage (e.g., the flexible element) extend along the support arm members the support arm provides a narrow profile that takes up less space while retaining the support arm and/or the display screen in a desired orientation.

Although selected advantages are detailed above, the list is not intended to be exhaustive. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention includes any other applications in which the above structures and fabrication methods are used. 

1. A support arm, comprising: an arm having a proximal arm pivot joint to provide a range of elevational rotation of the arm, and a distal component mount; a biasing device sized and shaped to provide an increasing force with increasing displacement; a flexible element coupled between the biasing device and the arm with a linkage between the arm and the biasing device wherein at least a portion of the flexible element forms a segment between the arm and the linkage and the segment is at an angle relative to the arm, wherein the angle varies during rotation of the arm; and wherein an arm end location of the segment is fixed in relation to the arm during rotation of the arm, and a linkage end location of the segment change in relation to the pivot joint during rotation of the arm.
 2. The support arm of claim 1, wherein the linkage includes at least one pulley.
 3. The support arm of claim 1, wherein the arm includes a four bar linkage.
 4. The support arm of claim 3, wherein the four bar linkage includes a second arm sized and shaped to correspondingly rotate with the arm, and another portion of the flexible element is coupled to the second arm.
 5. The support arm of claim 1, wherein the flexible element includes a metal cable.
 6. The support arm of claim 1, wherein the biasing device includes a tension spring.
 7. The support arm of claim 1, wherein the biasing device includes a compression spring.
 8. The support arm of claim 1, wherein the angle of the segment changes during rotation of the arm and the angle of the segment adjusts a moment applied to the arm by the biasing device throughout the range of elevational rotation of the arm.
 9. The support arm of claim 1, wherein the biasing device is progressively displaced throughout the range of motion of the arm, and the angle of the segment changes at a higher rate at least when the arm rotates below horizontal to adjust a moment applied to the arm by the progressively displaced biasing device.
 10. The support arm of claim 1, further comprising an additional pulley coupled with the biasing device to double displacement of the flexible element in relation to displacement of the biasing device.
 11. A support arm, comprising: a four bar parallelogram linkage arm having a proximal arm pivot end to provide a range of elevational rotation of the arm, and a distal component mount; a spring coupled to an upper member of the four bar linkage parallelogram; a flexible element coupled between a bottom member of the four bar parallelogram linkage arm and the spring with a pulley between the bottom member and the spring wherein at least a portion of the flexible element forms a segment between the bottom member and the pulley, and the segment is at an angle relative to the bottom member, wherein the angle varies during rotation of the arm; and wherein an arm end of the segment is fixed in relation to the bottom member during rotation of the arm, and a tangent location of a pulley end of the segment changes in relation to the pivot end of the arm during rotation of the arm.
 12. The support arm of claim 11, wherein the flexible element includes a metal cable.
 13. The support arm of claim 11, wherein the arm end of the segment can be adjusted within a range of locations along the bottom member to a plurality of locations, wherein a selected location in the range remains fixed in relation to the bottom member during rotation of the arm.
 14. The support arm of claim 11, wherein the angle varies during rotation of the arm between around 90 and −90 degrees.
 15. The support arm of claim 11, further including an additional pulley coupled to the spring to double flexible element displacement in relation to spring displacement.
 16. The support arm of claim 11, wherein the spring includes a compression spring.
 17. The support arm of claim 11, wherein the spring is progressively displaced throughout the range of motion of the arm, and the angle of the segment changes at a higher rate at least when the arm rotates below horizontal to adjust a moment applied to the arm by the progressively displaced spring.
 18. A system, comprising: a wheeled chassis; a support arm coupled to the wheeled chassis, the support arm including: an arm having a proximal arm pivot joint to provide a range of elevational rotation of the arm, and a distal component mount; a spring; a flexible element coupled between the arm and the spring with at least one pulley between the arm and the spring wherein at least a portion of the flexible element forms a segment between the arm and the at least one pulley, and the segment is at an angle relative to the arm, wherein the angle varies during rotation of the arm; wherein an arm end of the segment is fixed in relation to the arm during rotation of the arm, and a tangent location of a pulley end of the segment changes in relation to the pivot end of the arm during rotation of the arm; a display screen coupled to the distal component mount; and a processor unit in communication with the display screen.
 19. The system of claim 18, wherein the arm includes a four bar linkage arm.
 20. The system of claim 18, wherein the spring includes a compression spring.
 21. The system of claim 18, further comprising an additional pulley coupled to the spring, and the additional pulley and the at least one pulley are adapted to double cable displacement in relation to spring displacement.
 22. The system of claim 18, wherein the display screen includes a flat panel computer monitor.
 23. The system of claim 18, wherein the processor unit is located adjacent to the wheeled chassis.
 24. A method for making a support arm comprising: coupling a flexible element between a biasing device and a first member, and the first member includes a pivot joint, and the biasing device provides an increasing force with increasing displacement; and moveably coupling a linkage along the flexible element, and the linkage is between the first member and the biasing device, and at least a portion of the flexible element forms a segment between the first member and the linkage and the segment is at an angle relative to the first member, wherein the angle varies during rotation of the first member, and an arm end location of the segment is fixed in relation to the first member during rotation, and a linkage end location of the segment changes in relation to the pivot joint during rotation.
 25. The method of claim 24, wherein moveably coupling the linkage along the flexible element includes moveably coupling at least one pulley along the flexible element.
 26. The method of claim 25, further comprising coupling the at least one pulley to a second member, wherein the second member is adapted to correspondingly move with the first member.
 27. The method of claim 25, further comprising coupling an additional pulley between the biasing device and the flexible element, and the additional pulley is moveably coupled to the flexible element.
 28. The method of claim 24, further comprising coupling another portion of the flexible element to a second member, wherein the second member is adapted to correspondingly move with the first member.
 29. The method of claim 24, further comprising coupling a portion of the biasing device to a second member, wherein the second member is adapted to correspondingly move with the first member. 